本研究針對析出強化型高熵合金(Al0.2Co1.5CrFeNi1.5Ti0.3，Al02Ti03)透過雷射積層製造研究其微結構及機械性質，並且與鍛造製程下的Al02Ti03高熵合金以及雷射積層製造的傳統合金IN718進行微結構及機械性質比較。
雷射積層製造Al02Ti03高熵合金在本實驗中具有極高的緻密度(>99.9%)，此合金在室溫時比起鍛造製程Al02Ti03高熵合金降伏強度增加了285 MPa，比起雷射積層製造IN718 降伏強度增加了229 MPa，雷射積層製造Al02Ti03高熵合金在高溫下也展現較佳的機械性質，相對於鍛造製程Al02Ti03高熵合金及雷射積層製造IN718降伏強度分別增加了138MPa 及98MPa。
透過分析各個強化機制以及進行微結構上的比較，發現由於雷射積層製造的快速冷卻特性，使雷射積層製造Al02Ti03高熵合金對比鍛造製程具有較小的晶粒，也由於此特性使Al02Ti03高熵合金具有較多的殘留應力存在其中。除了以上原因，由於Al02Ti03高熵合金成分中具有較高比例的鈦，使得在雷射積層製造的過程中，殘留在腔體中的氧氣被材料所吸收，形成奈米等級的鈦氧化物，這些氧化物均勻散佈在材料之中；此外，由於雷射積層製造中的微小偏析使材料在經過熱處理後生成不在平衡相圖下出現的L21相，這些奈米級顆粒也對材料進行強化，使雷射積層製造Al02Ti03高熵合金對比鍛造製程由更加的機械性質。
而對比雷射積層製造IN718，雷射積層製造Al02Ti03高熵合金擁有較高比例的γ’ 析出相，同時IN718低鋁鈦含量的特性，使雷射積層製造IN718不具有奈米級氧化物，而以上原因使得雷射積層製造Al02Ti03高熵合金具有較佳的機械性質，同時因為雷射積層製造IN718不具有奈米級氧化物，這導致雷射積層製造IN718相對於雷射積層製造Al02Ti03高熵合金具有較高程度的晶界偏好方向。

A precipitation strengthened high entropy alloy (HEA) - Al0.2Co1.5CrFeNi1.5Ti0.3 (Al02Ti03) was fabricated successfully with selective laser melting (SLM) method. Nano-sized titanium monoxide dispersion was observed after the SLM process. Formation of L12 and L21 particles occurred after direct ageing at 750 ℃ for 50 hours. The presence of L12 precipitates, L21 phase, nano oxide, and dislocation network provided superior tensile strength comparing to those of cast and wrought (C&W) sample and Inconel 718 processed by SLM. The yield strength of aged Al02Ti03 processed by SLM was 285 MPa and 229 MPa higher than those of C&W Al02Ti03 at room temperature and 500 ˚C, respectively. The yield strength of aged Al02Ti03 processed by SLM was 138 MPa and 98 MPa higher than that of IN718 processed by SLM at room temperature and 500 ˚C, respectively. This work demonstrates that SLM process can contribute additional strengthening factors associated with the high entropy composition.

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